System for the selective stacking of sheet material



NOV. 4, 1969 UNGERER 3,476,241

SYSTEM FOR THE SELECTIVE STACKING OF SHEET MATERIAL Filed NOV. 30, 1967 2 Sheets-Sheet l NOV. 4, 1969 F, UNGERER 7 3,476,241

SYSTEM FOR THE SELECTIVE STACKING OF SHEET MATERIAL Filed Nov. 30, 196'? 2 Sheets-Sheet 2 C B A FIG.3 l 9 i v I E v 12 E J 31 30 30 w-| m l L J 4: I] l 26 i 15 i ig 15' 28 c' B A 32 F/Qs E g United States Patent 0 3,476,241 SYSTEM FOR THE SELECTIVE STACKING 0F SHEET MATERIAL Fritz Ungerer, deceased, late of Pforzheim, Germany, by

Irma Ungerer, sole heir, Friedenstrasse 86, Pforzheim,

Germany Filed Nov. 30, 1967, Ser. No. 688,650 Claims priority, application Germany, Dec. 1, 1966,

Int. Cl. B07c 3/68,- B65h 29/58 US. Cl. 20973 9 Claims ABSTRACT OF THE DISCLOSURE connected through valved ports to a pressure source. By

means of appropriate signals selective or grouped lower chambers are disconnected from the vacuum source and connected to the pressure source causing the sheet-like article immediately beneath the chambers to drop.

BACKGROUND OF THE INVENTION This invention relates to a system for the selective stacking and conveying of sheet material, such as metal sheets of determinate dimensions, by means of at least one stacking belt. The sheets are carried by the apertured stacking belt by adhering to the lower face of the lower flight thereof by virtue of vacuum applied by suction heads disposed in a stationary manner adjacent the upper face of said lower flight.

Systems of the aforenoted type are known in the art. Depending upon the position of the sheets during their travel, the operation of the suction heads is periodically interrupted, while other suction heads, disposed in the region of the stacking station and attracting solely the conveyor belt, are continuously operated. It is also known to connect the suction heads to conduits delivering pressurized air which, at the moment of shutting off the suc tion conduits, are periodically opened depending upon the position of the corresponding sheet. In such an apparatus, which is described in United States Patent No. 3,123,354 to F. Ungerer, the sheets are taken from a conveyor belt and conveyed to a position above the stacking station where all sheets are deposited by the aboveoutlined control of the suction heads.

The above-described apparatus does not provide for the possibility of further conveying the sheets to another stacking station disposed in the direction of advance of the sheet and to deposit at the first stacking station only selected ones from all the conveyed sheets.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention to provide an improved system over United States Patent No. 3,123,354 for selectively stacking sheet-like articles.

It is another object of the invention to provide an improved system over United States Patent No. 3,123,354 for selectively stacking sheet-like articles according to their thickness tolerances wherein said improved system is adapted to handle sheets of different lengths.

Briefly stated, according to the invention, in at least one of the suction heads there is provided an upper suction chamber continuously connected to a vacuum pump and under the upper suction chamber there are serially disposed in the longitudinal direction of the stacking belt a plurality of lower chambers which, at their base adjacent the upper face of the lower flight of the stacking belt, have at least one suction opening. The lower chambers communicate with the upper suction chambers through at least one first valve and communicate with the ambient atmosphere or with a source of pressurized air by means of at least one second valve. By controlling the valves, the lower chambers may be independently or as a group connected to the upper suction chamber and to the ambient atmosphere (or to the source of pressurized air) dependent upon the position of the sheet to be deposited. It may thus be achieved that sheets having substantially different lengths may be conveyed and any selected sheet may be deposited at any selected stacking station, while the other sheets may be transported to a subsequent station.

The invention will be better understood and further advantages as well as objects will become more apparent from the ensuing specification of a preferred embodiment taken in conjunction with the drawings.

The preferred embodiment, the description of which will now follow, includes three serially arranged stacking stations each associated with a plurality of suction heads constructed according to the invention. The transported sheets are selectively deposited at one of the three stations according to the sheet thickness sensed by a suitable gauge which, by means of signals transmitted to the appropriate stacking station, controls the operation of the novel suction heads and thus causes the sheets to be deposited by the appropriate stacking station.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic elevational view of the system according to the invention having three stacking stations and control means therefor;

FIG. 2 is a schematic elevational view of an enlarged portion of FIG. 1 in more detail;

FIG. 3 is a schematic sectional view of a suction head according to the invention taken along a line normal to the direction of sheet feed;

FIG. 4 is a view along lines AA of FIG. 3;

FIG. 5 is a view taken along lines BB of FIG. 3; and

FIG. 6 is a view taken along lines CC of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Turning now to FIG. 1, there are shown three stacking devices generally indicated at 1, 2 and 3 serially arranged and interconnected by means of conveyor belts 4, 4'. The stacking system is supplied with sheets 19 by means of a conveyor belt 5. The sheets 19 are cut from a coil (not shown) by means of a flying shear 21 arranged, when viewed in the direction of the sheet feed, behind a straightening apparatus 20. The shearing device 21 is associated with a thickness gauge 22. Referring to FIG. 2, each stacking device 1, 2 and 3 includes a stacking belt 18 driven by a motor M and trained about driving rollers and idlers. Adjacent the upper face of the lower flight of stacking belt 18 there are provided suction heads 6 exerting a continuous suction force to the stacking belt and suction heads generally indicated at 7-11 imparting a lifting force to the sheets 19 which thus adhere to the lower face of the lower flight of stacking belt 18.

Each of the suction heads 7-11 comprises an upper suction chamber 13 which is coupled to a vacuum pump (not shown) by means of a port 12. Below each upper suction chamber 13 there are serially disposed three rectangular chambers 14, 15 and 16, the long side of each of which is arranged parallel to the belt width. While the width of each suction head 7-11 and that of its upper suction chamber 13 correspond to the belt width, each of the chambers 14, and 16 is somewhat shorter than half of the belt width. Reference is had here to FIG. 3 which shows one of the suction heads (suction head 9) in section taken transversally to the width of stacking belt 18. Adjacent each chamber 14, 15 and 16 there is disposed, in the direction of the belt width, over the other half of the belt and under the upper suction chamber 13, a second identical chamber (only one shown at 15'). Between each chamber 14, 15, 16 on the one hand and its adjacent identical chamber (only 15 shown) extending across the width of the belt on the other hand, there are disposed under the upper suction chamber 13 lower suction chambers 29, 29 and 29" (FIGS. 3 and 4). Also, under the upper suction chamber 13 and adjacent the outer end of each chamber 14, 15, 16, as well as adjacent the outer end of each corresponding identical chamber (only 15' shown), there are provided, along both opposed edges of the stacking belt, lower suction chambers 28. All shown lower suction chambers 28, 29, 29 and 29" communicate continuously with the upper suction chamber 13 by means of openings 30. The lower suction chambers are, similarly to the chambers 14, 15 and 16, open at their base which is adjacent to the upper face of the lower flight of the stacking belt. The belt portions passing immediately below the lower suction chambers are hole-free so that the vacuum applied by the lower suction chambers aflects solely the stacking belt. Each chamber 14, 15, 16 and the identical adjacent chambers (only 15' shown) are connected with the upper suction chamber 13 by means of two conical valves 31 (only one shown). These conical valves are of such a light structure that they are normally held open by means of the suction stream generated in the upper suction chamber 13. The valves 31 may be closed by a pneumatically-operable cylinder-piston assembly 34. Further, each chamber is provided with two ports 32 (only one shown) having solenoid valves 33. Ports 32 connect the said chambers to a source of pressurized air.

Turning once again to FIG. 1, with each stacking device 1, 2 and 3 there is associated an approach switch 23, 24 and 25, respectively. The approach switch 23 of the stacking device 1, which, as it will be seen, deposits or stacks rejected sheets, is connected to a current source through a motion pick-up 26 and a switch 27 operated by the flying shears 21. The switch 27 is controlled by an impulse transmitter 35 which sends a signal when, during each cutting operation effected by the flying shears 21, the thickness of the sheet sensed by gauge 22 is outside a value of preset coarse tolerances. Similarly, the approach switch 24 of the stacking device 2, which stacks sheets of second quality, is connected to a current source across a motion pick-up 36 and a switch 37 actuated by the flying shears 21. The switch 37 is actuated by an impulse transmitter 35' which sends a signal when, during each cutting operation effected by the flying shears 21, the thickness of the sheet sensed by gauge 22 is outside a value of preset fine tolerances. The approach switches 23 and 24 are also connected to a current source through push buttons 38 and 39. The approach switch 25 of the stacking device 3, where sheets of first quality are deposited, is continuously connected to a current source and is thus constantly in a standby condition.

OPERATION OF THE PREFERRED EMBODIMENT The precedingly-described system operates in the following manner.

Should the thickness gauge 22 sense a substantial devialion above or under the maximum tolerances of a sheet thickness when a sheet is cut, the impulse transmitter emits a control pulse causing switch 27 to be closed by the flying shears 21 and causing the approach switch 23 to be supplied across the motion pick-up 26 with operational voltage and thus to be placed in a standby condition. If now the sheet, the thickness of which has just been sensed, during its advance over the conveyor belt 5 and stacking device 1, actuates with its trailing edge the approach switch 23, the latter, by means not shown, energizes the pneumatic piston-cylinder assemblies 34 whereby the conical valves 31 of the chambers 14 and 15 will close. Simultaneously, the solenoid valves 33 in the ports 32 will open, whereby air under pressure will stream into chambers 14 and 15 now shutoff from the upper suction chamber 13. Thus, in chambers 14 and 15 the vacuum will disappear and pressure will build up. The sheet with unacceptable thickness, which is somewhat shorter or at most as long as the total added width of chambers 14 and 15 and which is disposed exactly under these chambers during the actuation of the valves, will drop onto a stacking table disposed under the stacking belt 18. Since the valves 31 and 33 associated with chamber 16 have not been actuated, this chamber continues to be under vacuum and exerts a holding suction force to the sheet held on the stacking belt in front of the released sheet and thus is further transported towards the successive stacking device. The vacuum in lower suction chambers 28, 29 remains unaffected by the control of chambers 14, 15 and 16 and thus continuously and firmly attracts the stacking belt along its hole-free zones.

In case the thickness gauge 22 senses only an insignificant deviation from the tolerances of thickness, then, instead of the approach switch 23 of the stacking device 1, the approach switch 24 of the stacking device 2 (for sheets of second quality) will be operated and placed in a standby condition the same way as was described in connection with approach switch 23. The corresponding sheet then falls on the stack under the stacking device 2. By manipulating push buttons 38 and 39 an operator may, upon observation of surface defects or other defects not detected by the thickness gauge, cause the sheet to fall onto the stack under the stacking devices 1 or 2, respectively.

When the gauge 22 senses thicknesses that are Within the desired tolerances, neither impulse transmitters 35 or 35' is actuated and consequently both approach switches 23 and 24 remain unenergized. Thus, the corresponding sheets will arrive at stacking station 3 where the continuously energized approach switch 25 will cause them to drop and be stacked as sheets of first quality.

By suitably connecting the valves of several chambers to the approach switches, the stacking devices may be adjusted for dropping sheets of any desired length. It is further within the scope of the invention to provide stacking devices with long stacking belts and a plurality of approach switches and suction heads associated therewith.

Although only one embodiment of the invention has been depicted and described, it will be apparent that this embodiment is illustrative in nature and that a number of modifications in the apparatus and variations in its end use may be effected.

That which is claimed is:

1. In a system for selectively stacking sheet-like articles of the type including at least one perforated stacking belt having a lower flight and an upper flight, stationary suction heads disposed immediately above the upper face of said lower flight, said sheet-like articles being adapted to be carried by said stacking belt by adhering to the lower face of said lower flight thereof by virtue of vacuum applied by said suction heads, means to discontinue said vacuum causing said sheet-like article under said suction heads to drop by gravity, the improvement comprising,

(a) an upper suction chamber disposed in at least one of said suction heads, said upper suction chamber being in continuous communication with a vacuum source,

(b) a plurality of lower chambers within said at least one suction head disposed serially along the length dimension of said stacking belt and under said upper suction chamber, each of said lower chambers having a base provided with at least one suction opening immediately adjacent the upper face of the lower flight of said stacking belt,

(0) at least one first valve disposed between each of said lower chambers on the one hand and said upper suction chamber on the other hand,

(d) at least one second valve disposed between each of said lower chambers on the one hand and a fluid source adapted to supply fluid of at least atmospheric pressure on the other hand, and

(e) control means for operating said valves to alternately connect selected ones of said lower chambers to said upper suction chamber and to said fluid source, said control means adapted to be actuated by said sheet-like articles.

2. An improvement as defined in claim 1, wherein each lower chamber is connected with said upper suction chamber by port means provided with at least one of said first valves of conical shape and of light structure, each last-named valve is biased open by the vacuum in said upper suction chamber and is closable by pneumatic means.

3. An improvement as defined in claim 1, wherein said first and said second valves are adapted to be simultaneously oppositely actuated.

4. An improvement as defined in claim 3, wherein said second valves are electromagnetically operated and are contained in port means interconnecting said lower chambers with said fluid source.

5. An improvement as defined in claim 4 including manually adjustable throttle flaps disposed in said port means.

6. An improvement as defined in claim 1, wherein said upper suction chamber extends substantially across the entire Width of said belt, said lower chambers are arranged in rows parallel with said width and in columns parallel with the length dimension of said belt, between each said lower chamber of the same row there are disposed lower suction chambers continuously communicating with said upper suction chamber and applying vacuum to imperforate zones in said belt.

7. An improvement as defined in claim 1 including a plurality of serially disposed stacking belts, each stacking belt is associated with at least one suction head having said upper suction chamber and said lower chambers, one of said control means is associated with each of said stacking belts and impulse transmitting means for selectively placing any of said control means in a standby condition rendering it responsive to said sheet-like articles.

8. An improvement as defined in claim 7 including a thickness gauge disposed in the path of travel of said sheetlike articles and upstream of said stacking belts, said gauge is operatively connected to said impulse transmitting means and is responsive to predetermined thickness tolerances in said sheet-like articles.

9. An improvement as defined in claim 7, wherein said impulse transmitting means include manually operable push button means for placing a selected one of said control means in said standby condition.

References Cited UNITED STATES PATENTS 2,969,869 1/1961 Klinger 271-74 X 3,081,996 3/1963 Hajos 27l--74 3,101,942 8/1963 Zyber 27174 X 3,202,302 8/1965 Insolio 27174 X 3,399,587 9/1968 Lee et a1. 271-74 X ALLEN N. KNOWLES, Primary Examiner US. Cl. X.R. 

